Variable condenser



Sept. 6,1927. L L JONES 1,641,438

VARIABLE coNDENsER A Filed Dec. 13, 1923 JJ f4 j v l INVENTOR F.j.2b/V15: 1f Z3 BY L z/4 E ATTORNEYS Patented Sept. 6, 1927.

UNITED .STATES PATENTI OFFICE.

LESTER I.. JONES, or onADELL, NEW JERSEY.

VARIABLE CONDENSER.

Application led December 13, 1923. Serial No. 680,465.

This invention relates to a variable con` pending application 'forCapacitive coupling control system, Serial No. 607 ,046,

filed Dec. 15, 1922, the present application being a division andcontinuation 1n rpart of the said copending application.

The principal objects of my present invention include the provision of avariable compensating condenser designed for employment with relay oramplifier tube circuits in which the feed back of energy from the outputto the input circuit due to the unavoidable capacitive coupling betweenthe circuits is desired to be compensated or neutralized; the furtherrovision of a compensating condenser of t iis nature which vis madeadjustable to adapt the same to different makes ory types of relay oramplifier tubes, and which is provided with means for preventing thedetuning of the input circuit during condenser adjustment; the stillfurther provision of a condenser of this nature in which the elementsthat are adapted for connection to high potential points of thereceiving circuit are electrostatically shielded, and in whichfurthermore the parts are so inter-related that in spite of the very lowcapacity values of the condenser .(of the order of 10 1n. In. f.,s)adjustment is unvaffected by the hands or body of the operator `or userin obtaining a setting 0f the same.

To the accomplishment, of /the foregoing and such other objects as mayhereinafter appear, my invention consists in the'elements and theirrelation one to the other, ashereinafter particularly described andsought to be defined in the claims, reference b eing had to theaccompanying drawings which show' preferred embodimentsA of myinvention, and in which Fig. 1 is aview taken in cross-section of oneform of my compensator condenser,

Fig. 2 is a cross-'sectional view -of a modification thereof.

Fig. 3 is a view taken in cross-section on the line 3-3, Fig. 2,

Fig. 4 is `a perspective view showing the parts detached and the mannerof 'assembling the same, and.

l Fig: 5 is a diagram of a relay or amplifylng c1rcu1t showing myinvention applied thereto.

Referring first to Fig. 5 of the drawings,

I show7V an amplifier or relay tube circuit system for exemplifying acontemplated mode of application or use of my invention.

The relay tube system comprises an electron i discharge or thermionicrelay including the Ii'ament 10 which is heated to incandescence by thebattery 11 connected thereto for producing the electron stream, thecontrolling grid 12 and the controlled plate 13,.the grid beingconnected to a controlling` or input circuit i and the plate beingconnected to a controlled or output circuit o. i

The input circuit is provided as usual with an inductor 14 which may becoupled for energy reception to an induction coil of an antennae circuitand a variable condenser.15 connected in parallel tothe inductor 14, thecondenser being adjustable,fas is well known, for varying the tuningcharacteristics or period of the input circuit to syntonize the same tothe desired incoming frequency,

`the said inductor and condenser being connected to the grid or highpotential side of the input circuit and to the lament by means of theconductors 16 and 17 respectively. v

The output circuit o is provided with an external or output impedance 18connectedy at one end by means of a conductor 19 to the plate 13 andconnected at the other end by means ofthe conductor 20 to the positiveterminal of the battery 21, the negative terminal of which is connectedto vthe filament 10, as clearly shown in the drawings. The outputinipedance 18 may as shown comprise the primary of a transformer `and iscoupled to a secondary (not shown), the said secondary receiving theamplified energy for rectification or further amplification if desired.4 l

As explained in the above mentioned parent application, due to thenormal Unshield- `able capacity between the plate 13 and the grid 12 ofthe electron discharge tube, some of the energy in the output circuit isobjectionably retransferredy or fedback to the input circuit, the grid12 being charged byv the plate 13 through the capacity therebetween. Forcompensating for this feed back to 'reduce or entlrely leliminate theeffect of the same, I provide means for neutralizing in part -or inwhole the charge carried from sof . put circuit simultaneously" theplate to the grid. This result I accomplish by providing means forimpressing on the grid 12 a charge which may be less than, equal to, orgreater than in magnitude but opposite in sign to the charge carriedthereto from the plate; and to this end Iprovide means for creatingI apotential .opposite'to the otential on the plate and impressing the saipotential on a capacity means connected to the grid 12. Where feed backis desired to be entirely eliminated, the product ofthe said potentialand the capacity is made equal to the charge transferred to the gridfrom the output circuit.

. For creating the opposite potential, I p rovide an additionalimpedance 23 comprising a coil wound in the same direction as the outputimpedance coil 18 closely cou led to the same and lhaving a number oturns preferably equal to the number of turns in the winding 18, thesaid additional impedance being connected at one end to the conductory20 and at its other end by means of a conductor 24 to a condenser 25which is connected as shown to the high potential side of the inputcircuit by means o a conductor 26, the said condenser being preferablymade equal to the capacity between the grid and the plate and thecapacity between the 'conductors or leads connected thereto (of theorder of 6 m. m. f.s for present-day receiving tubes). By creating apotential opposite in sign to the potential on the plate 13 and byimpressing the same on the condenser 25, it will be apparent that vthegrid 12 is supplied with an electric charge which is equal and oppositeto the charge fed back thereto from the plate 13,'this equalization orneutralization of the charge preventing the setting up of objectionablelocal oscillations in the input circuit.

For the purpose of ad'usting the compensating e ect to adapt t e saineto different relay tubes, the internal capacities of which vary, and tothe capacity of the leads which may vary in dilerent receiving sets, thecondenser 25 is made variable; and to this end includes a movable plateor ele ment a and a stator plate or element c, the ormer being movablewith respect to the latter in opposite directions, as indicated by thearrows in'Fig. 5.y

-In vievy7 of the ne ligible impedance of the coil 23 as compare withthe impedance of the grid coil 14, the chan e of capacity be# tweentheplates a and c urin adjustment is normally effective for modigyingthe capacity of the grid circuit and hence the period of the same. Forthe purpose' of preventing this variation of capacity of the condenserfrom varying the tuning characteristics or period vof t e cuit, I havefound it desirable to provide means for varying the capacity of theinand inversely in id or input cir-v correspondence with the varying ofthe capacity of the equalizing circuit. To this end the condenser 25includes a third and stator plate or element b connected to the filamentside of the input circuit by means of a 'conductor 27, said filamentside of the circuit being preferably grounded as shown yfor varying thecapacity of one plate set inversely with respect to the other plate set.By the provision of this construction it will be seen that the effectivegrid circuit capacity may be maintained constant dur ing adJustment ofthe condenser plate a so that the tuning oi' period of the grid or inputcircuit is maintained.

The three-plate condenser of my invention may constructionally take theform shown in Fig. 1 of the drawings, in which the three plates comprisecylinders or tubes a', b and c', the tubes b and c being fixed orstationary and forming the stator element and the tube a beingtelescopically movable in opposite directions between the tubes .b and cand formng the movable element. The tube a is provided with a connectingmeans 29 for connection to the high potential side of the grid circuit,the tube b is provided with a connecting means 30 for connect-ion to thefilament and ground end of the circuit, and the filament c is similarlyprovided with a connecting means 31 for connection to the impedance ofthe equalizing circuit. The tube b may be ixedly carried by a collar 32,the said collar being threadedly received by a threaded bushing 33 whichis stationarily mounted on a panel board 34, the panel board beingsecured between the shoulder 35 of the bushing 33 and the collar 32.Fitting within the tube b', I provide 'a tube of insulating material 36such as hard rubber on which the tube c is fixed by means of theconnecting element 3l, the tube a being constructed to telescopicallyslide .in the tube of insulating material.

For `moving the plate element a', there is providedethe shaft orspindle'37 made of electrically conductive material which is threadedthe greater part of its length as shown at 38 for threaded engagementwith a tapped member 39 ilixedly carried by an insulating dial member 40which carries a plate sets ac and ab, moveics pointer 41. The shaft islongitudinally recessed as at 42 for receiving a pin 43 fitted and thecomplemental stop pin 4T car' tached to the shaft 37 as by, beingthreadedy thereto, as shown in the drawings. For

shielding the high potential elements of the condenser from the hand ofthe operator, the shaft 37 is conductively connected to the stator plateb which is to be connected to ground, the conductive connection beingprovided by making the parts 32, 33, 35 and 39 ot' electricallyconductive material. With Vthis arrangement the plate b provides aground shield for the condenser elements Referring now to Figs. 2 to 4of the drawings, I show a modification of my compensator condenser inwhich the adjustment from maximum capacity of one plate set to maximumcapacity of another plate set is obtained through a half-revolution ofthe operating shaft. In this construction the movable element a2 iscarried b an insulating body or plate 44 ixed tot e metallic shaft 37and the stator elements b2 and c2 are fixedly attached to 'an insulatingplate'or body 45, they said plate a2 being provided with the connectingmeans 29 and the plates b2 and 02 being provided respectively with theconnecting means 30 and 31', a sheet of dielectric material 36 beingarranged between the stator and movable plates. For limiting themovement of the rotor plate with respect to the stator plate, I providethe two stop pins 46 carried by the insulating body ried by theinsulating body 44', the sheet of dielectric material 36 being providedwith a slot 48 through which the in 47 projects, as clearly shown inFig. 2 oi'the drawings.

For shielding the high potential .elements of the condenser inthe formof construction shown in Figs.' 2 to 4 of the drawings and forconnecting the shaft 37 to ground, I

" provide a separate electrostatic shield 48 which forms a carrier forthe parts of the condenser, the said shield being connected `to theground plate b2 'by means of the securing element 49, the shield plate48 being cut or stamped out of sheet metal in a manner to provide thespring fingers 49', 49', the lower endsof which surround and engagetheshaft 37',- as clearly shown in Fig. 3 of the drawing. By means ofthis construction it will be evident that when the plate b2 is grounded,the shaft 37 .and the shield plate 48 are both at ground, otential.

In mounting this compensator con enser on a support or panel 34', thedial 40 is secured to the shaft 37 and aspring washer 50 is insertedbetween the panel and the dial to hold the condenser plates in properlyspaced relation.

The manner of constructing and using my compensatorcondenser will in themain be apparent from the above detailed description thereof and themode of application of the same. It will be further apparent that whileI have shown ythe compensator condenser in the preferred forms, thatnumerous changes may be made therein without departing from the spiritor principle of the invention. It will be obvious, for example,

that while I prefer to provide a single con-v denser element in therotor common to both condenser plate sets, that this may be varied inmany ways to accomplish the same. result. It will be also obvious thatthe parts'may be re-arran ed without departing. from the essence of t einvention defined in the following claims.

I claim: v

1. A variable condenser comprising a plurality of plate sets includingtwo independent stator elements, a movable element capacitively relatedto both stator velements and a shaft insulatably carrying the movableelement and conductively connectedA to one of said stator elements.

2. A variable condensercomprising a plurality of plate sets includingtwo stators and a rotor common to the stators, rotation of the rotorbeing effective for varying the capacity of one plate set inversely withrespect to the other, and a shaft made of an electrically conductivematerial insulatably carrying the rotor and conductively connected toone of the stators.

3. A variable condenser comprising a plurality of plate sets includingrelatively movable elements, and means for moving the movable element tovary the capacit of one plate set inversely with respect to the otherplate set, said means including van electrically conducting shaftinsulatably carrying the movable element and conductively connected toastationary element.

4. A variable'oondenser comprising a plu- 'rality of' plate setsincluding two stator plates and avrotor plate arranged so that whenrotated throug capacity betweenthe plates will be varied a halfrevolution the lill' lli from maximum ca pacity of one plate set to imaximum capacity of another plate set, and a shaft insulatablycarryingthe rotor element and conductively connected to one of -4 thestator elements.

5. A ,variable condenser rcomprising a plurality of plate sets includingrelatively movable elements, a shaft insulatably Carrying the movableelement, and an electrostatic shield conductively connected to saidshaft land to a stationary element.

62A variable" condenser vcomprising a plurality of plate sets includingtwo stator elements, a movable element, a shaft made of an, electricallyconductive material insulatvably carrying the movable element and anrality of plate sets including two stator elements, a movable element, ashaft made 'of an electrically conductive material insulatably carryingthe movable element and an electrostatic shield conductively connectedto said shaft and t0 one of said stator elements. 8. A variablecondenser comprising a plu rality of plate sets including relativelymovable elements, a shaft insulatably carrying the movable element, andan electrostatic shield conduetively connected to said shaft.

9. A variable condenser comprising a pair of independent stator plates,a rotor plate common to the stator plates, a conducting shaftinsulatably tarrying the rotor plate and a stationary electrostaticshield conductively connected to the shaft.

10. A variable condenser lcomprising a pair of independent statorplates, a rotor plate common to the stator plates, a conucting shaftinsulatably carrying the rotor plate and a stationar electrostaticshield conductively connecte to the shaft and to one of said statorplates.`

11. A variable condenser comprising a plurality of plate sets includingrelatively movable elements and means for operating the elements to varythe capacity of one plate set inversely with respect to the other plateset, and an electrostatic shield conductively connected to a stationaryelement of said plate sets.

Signed at New York New York and State of day of December, A. D. 1923.

LESTER L. JONES.

iNty in the county of ew York, this 8th

